Naphthalimide compounds are used in tissue bonding and protein cross-linking applications. When activated by an activating agent, such as light in the 400-500 nm absorption range, the naphthalimide compounds form chemically-reactive species that cross-link proteins, bond connective tissues together, and bond tissues and other biomaterials together. A naphthalimide-labeled biomolecule, such as a naphthalimide-labeled chitosan, is also capable of bonding tissues without subsequent direct illumination of the contacted tissue area. The naphthalimide compounds may be used in tissue or arterial repair, stabilization of an expanded arterial wall after angioplasty, tethering pharmaceutical agents to tissue surfaces to provide local drug delivery, and for chemically bonding skin care products, sunscreens, and cosmetics to the skin.